1. Field of the Invention
The present invention relates to a display apparatus and a manufacturing method thereof, in which defects caused by a short circuit between conductive layers sandwiching an insulating film can be prevented, enabling an improvement in yield.
2. Description of Related Art
As disclosed in Japanese Unexamined Patent Application Publication No. 8-254712, in active matrix type liquid crystal display apparatuses of recent years, a lateral electric field method, in which the direction for applying an electric field to the liquid crystal is set parallel to the substrate, has been used principally as a method for obtaining an ultra-wide viewing angle. It is known that by employing this method, contrast variation and gradation inversion, occurring when the viewing angle direction is varied, can be substantially eliminated.
In Japanese Unexamined Patent Application Publication No. 8-254712, a pair of counter electrodes are disposed at a remove from each other on either side of lower layer source wiring. Thus, when a voltage is applied to the source wiring, an electric field is generated by the voltage, and as a result, the orientation of liquid crystal provided between a thin film transistor (to be abbreviated to TFT hereafter) array substrate and a color filter substrate is varied. To prevent this, the width of the pair of counter electrodes must be increased, thereby limiting light transmission, and as a result, the aperture ratio of a display area decreases.
To solve this problem, a device structure employing a lateral electric field method has been disclosed in Japanese Unexamined Patent Application Publication No. 2003-307748, for example. In Japanese Unexamined Patent Application Publication No. 2003-307748, a counter electrode covers the source wiring such that the two overlap. According to this constitution, the electric field generated by the source wiring is blocked by the counter electrode, and therefore the electric field does not affect the liquid crystal, enabling a reduction in variation of the liquid crystal orientation. As a result, the width of the counter electrode which limits light transmission can be reduced, enabling an increase in the aperture ratio.
This technique of overlapping the source wiring and the electrode thereabove to increase the aperture ratio is applied similarly in a conventional method, where the electric field is applied to the liquid crystal in a perpendicular direction to the substrate, and is disclosed in Japanese Unexamined Patent Application Publication No. 9-325358, for example. In this method, a counter electrode opposing a pixel electrode is formed on a color filter substrate which is adhered to a TFT array substrate on which the pixel electrode is formed.
Japanese Unexamined Patent Application Publication No. 2001-249345 discloses a liquid crystal display apparatus in which a TFT array substrate and a color filter substrate are adhered to each other via a conductive sealing pattern serving as an adhesive layer. Common electrode wiring formed on the TFT array substrate and a common electrode formed on the color filter substrate are electrically connected via the conductive sealing pattern. The common electrode serves as a counter electrode opposing a pixel electrode.
However, in the case of Japanese Unexamined Patent Application Publication No. 2003-307748, the upper layer counter electrode covers the lower layer source wiring via an interlayer insulating film such that the two overlap. Hence, when pin holes, fractures, and so on occur in the overlapping region of the interlayer insulating film, an electrical short circuit occurs between the upper layer counter electrode and lower layer source wiring, leading to a display defect which causes problems such as a reduction in yield and a decrease in reliability.
Further, in the case of Japanese Unexamined Patent Application Publication No. 9-325358, the upper layer pixel electrode and the lower layer source wiring overlap partially via an interlayer insulating film, and hence similar problems to those described above occur.
In the case of Japanese Unexamined Patent Application Publication No. 2001-249345, the conductive sealing pattern for adhering the TFT array substrate to the color filter substrate is applied so as to surround an display area of the liquid crystal display apparatus formed on the TFT array substrate. Hence, when pin holes, fractures, and so on occur in a region of the interlayer insulating film where the conductive sealing pattern and the lower layer source wiring overlap, an electrical short-circuit occurs between the lower layer source wiring and the common electrode formed on the counter substrate via the conductive sealing pattern, leading to a display defect which causes problems such as a reduction in yield and a decrease in reliability.
Defects in the interlayer insulating film such as pin holes and fractures may be caused by air bubbles in resist used to form a resist pattern during patterning, air bubbles contained in a liquid developer used during resist development, or foreign matter infiltrating the interlayer insulating film during film deposition, for example. Therefore, it is difficult in practice to eliminate these defects completely.
An object of the present invention is to obtain a display apparatus and a manufacturing method thereof with which inter-electrode short circuits caused by pin holes and other defects in an interlayer insulating film can be prevented, enabling improvements in yield and reliability.